Those of us who don’t know a lot about 4chan and DDos-ing and all the other touchstones of cyberlife will be happy to know that hackers who want to fight against power still turn to an age-old prank: they order pizza.

Sending pizza to people who don’t want it — and sometimes covertly watching from behind the drapes as it’s delivered — has been a technique of harassment since the days of rotary telephones.

It’s still part of the arsenal of Anonymous, the worldwide group of loosely connected pranksters (“the rude boys of activism,” they’re called in the documentary We Are Legion, as well as “the final boss of the Internet”) who are at the vanguard of a new kind of social activism.

Anonymous is famous for their DDos (that’s Denial of Service) of PayPal when the company withdrew its services from WikiLeaks, an organization Anonymous approves of. The many computer hackers who call themselves Anonymous — and wear the Guy Fawkes masks from the movie V for Vendetta, a face that has become symbolic of mass protest — overwhelmed PayPal’s computers until they crashed.

They also went to war against the Church of Scientology because it dared to pull down a video of Tom Cruise bragging about the powers of its members, a video that fit right into the Anonymous culture, i.e., they made fun of it. They take some credit for the revolutions in Egypt and Tunisia, where they helped keep the Internet going when despotic regimes tried to close them. They helped overthrow right wing radio host Hal Turner.

They did it through hacking and marching — thousands stood outside Scientology buildings around the world, chanting, “Don’t drink the Kool-Aid” and “Brainwashed” — and, in several cases, by ordering pizzas to be delivered to people’s houses. You get the feeling that if they could have soaped people’s windows on a website, they would have done that as well.

We Are Legion is an encyclopedic history of the movement that began — in spirit anyway — with a bunch of MIT students putting cars on the roofs of buildings and has become a formidable force for … well, it’s hard to say what exactly. Freedom of speech certainly, political justice sometimes, or just cruel fun occasionally.

When Anonymous found its political muscle in the Middle East and in assisting WikiLeaks founder Julian Assange, a spinoff group (“stop ruining our bad name”) did things like hacking into an epilepsy website with flashing images that would cause seizures.

That’s one of the few negative notes found by filmmaker Brian Knappenberger, who traces Anonymous from anything-goes websites like 4chan and /b/board — where photos ranging from cute cats to perverse sexual acts provide an illuminating window into the human psyche — to the more serious ends of Anonymous.

The Cruise video helped galvanize them into a “Declaration of War” that stated, “We are Anonymous. We are legion.”

It became a sort of electronic arm of the Occupy movement, a loosely connected group of people that, according to the film, include many attractive young women as well as the expected collection of 23-year-old men living in their parents’ basements. Someone says a lot of them had sex for the first time thanks to their Anonymous activities.

The connections, not to mention the technologies, are sometimes confounding, but We Are Legion keeps them mostly straight. It places the Anonymous movement in the context of traditional political protest: overwhelming an objectionable website is compared to sitting in a segregated lunch counter in Alabama, denying service to others. And if that doesn’t work, order the pepperoni.